Film driving apparatus



Jan. 20, 1970 G. CAPRARA FILM DRIVING APPARATUS 2 Sheets-Sheet 1 Filed Sept. 26, 196'? ATTORNEY Jan. 20, 1970 e. CAPRARA 3,490,667

FILM DRIVING APPARATUS Filed Sept. 26, 1967 2 Sheets-Sheet 2 ATTORNEY United States Patent Int. Cl. B6511 25/20 US. Cl. 226-25 14 Claims ABSTRACT OF THE DISCLOSURE An apparatus for frictional driving of photographic and/or cinematographic films of various widths, without acting on the perforations of the film; a winding circuit of almost constant length is given to the film so that the period of the film remaining immersed in the developing bath is always constant. Each driving shaft of the apparatus is driven by a motor; each motor is arranged to operate at two speeds. Lack of balance in the advancing of the film is eliminated by bringing one or more motors to a higher or balance speed and keeping others at a working or lower speed.

The subject of the present invention is apparatus for the frictional driving of photographic and/or cinematographic films of various widths.

As is known, it would be ideal for a photographic and cinematographic film-feeding device of the present type for use, for example, in a developing apparatus, to fulfill the following conditions:

(1) to make use of traction by friction without acting on the perforations of the film since the film may be without perforations;

(2) to be able to feed simultaneously films of various widths;

(3) to give the film a winding circuit of almost constant length so that the period of the film remaining immersed in the developing bath is always constant;

(4) to include safety means operating in all conditions and easy to regulate and to maintain;

(5) to be provided with regulating means which can be adjusted and kept in working order without stopping the machine; and

(6) to have the more delicate members well protected from the acids and corrosive liquid of the bath.

The existing devices for transporting film are classifiable into two large groups and the devices of both groups are far from able to satisfy these ideal conditions. A first group is constituted by traction means which act on the perforations of the film, such means ensure uniformity of advancing of the film but obviously can be used only for films provided with perforations and of the specific width for which the particular devices have been constructed. In addition the uniformity of advance does not prevent substantial variations in the time of immersion in the treatment bath as a consequence of the considerable expansion and contraction sustained by the film in the course of the treatment; such expansion and contraction causes the rollers which support the film to move away from or approach one another. A coupling so rigid and geometrically fixed is not the most suitable for treating a laminated rather fragile film particularly in relation to the perforations. In addition with such apparatus, there is difficulty in detecting irregularities and repairing the damage.

The second group of existing transporting devices includes those which indeed permit the treatment of films of various widths and not provided with perforations but in which such possibilities are more theoretical than practical.

Such means in fact are regulated mechanically or hydraulically by friction-varying mechanisms and must be set frequently by specialists. Such adjustments often have to be made with inefiicient apparatus, which is all that is available, or with the aid of tests made On test films. For this purpose considerable expenses for technical adjustments are incurred and low outputs must be tolerated; also, the film-processing laboratories are compelled to keep in working order reserve machines in order to ensure that work is fulfilled. Every time the type of film is changed the adjustments and the associated tests must be repeated.

An object of the present invention is to obviate at least some of the aforementioned drawbacks and to assist in the achievement of the ideal objectives mentioned above.

In order to attain these results it has been necessary to revolutionize the whole conventional traction technique and start from completely new and different principles.

Accordingly, I provide an apparatus in which the motion of each shaft of the system is effected by an auton omous motor apparatus, preferably electrically operable at two slightly different speeds capable of being selected at any moment by means of an on-ofl device. One of these two speeds, for example, the lower, speed is suitably set at all the autonomous motors so that in practice the lower speed determines the Working speed of the apparatus and will therefore in the following discussion be called the working speed, the higher and second speed will be described below as the balance speed. Setting of the electric motors to a particular speed may be easily made by means of a rheostat which is connected so as to be able to produce the desired difference in speed in a single-speed motor.

The axles of the autonomous motors are coupled directly or indirectly to the driving axles of the drawing spools; the motors are caused to operate at the working speed which is set on all the motors.

When the balance is disturbed due to an excessively high or an unusually low speed of the drawing of the film through the device, due to expansion, contraction or the like, in order to restore the balance it is suflicient to bring one or more of the autonomous motors concerned to the balance speed for a time sufiicient to eliminate the lack of balance and then to restore the working speed. Although all of the aforedescribed operations may be carried out manually by an operator, it is preferable to render the entire system automatic.

In order to make automatic operation possible, another function of the device is necessary; thus I provide means for producing a signal which triggers the switching of the motors from one speed to the other and vice versa. The ideal parameter for the regulation of this machine is the tension of the film, so that this parameter governs satisfactory operation and satisfactory results. Therefore in this apparatus, the film and the two series of spools disposed one on a fixed and one on a movable axle form a system which tends constantly to equi librium by which the tension of the film is maintained constant at all points. By the regulation of the drawing means use is made directly of the displacement of the axlesof the spools acting as movable rollers.

This problem has been solved with the present invention by use of the displacement of the axles of lower spools or rollers, acting as movable spools, for creating a local lack of equilibrium (disequilibration) in the tension of the film which, before it is transmitted to the whole system and is equalized is relieved and detected by a suitable member which gives the automatic signal necessary for switching the speed of the motors. One method of sensing the lack of balance is that of obstructing with resilient means the displacement of the movable rollers of the system beyond predetermined limits, so that such obstruction causes an instantaneous variation of tension the variation in tension is immediately detected and utilized by sensing means which may include members for controlling the speed variation of the motor or motors concerned. The sensing means is combined in a motorcoupling system designed so that the motor, which in effect has turned at a low working speed, is brought to the upper balance speed while the motor which has turned, in effect, at a high working speed, is maintained at that speed or brought to the low or working speed. Of course when the balance is achieved there is a return of both motors to the working speed.

In order to explain better the features of the present invention, reference is made to the accompanying drawing in which is shown, diagrammatically and by way of example, one embodiment of the invention.

In the drawing:

FIG. 1 shows diagrammatically, partly in elevation and partly in section, a machine incorporating apparatus according to the present invention;

FIG. 2 is a plan of the machine of FIG. 1, partly broken away;

FIG. 3 shows in section, the machine of FIG. 1, the section is taken on the plane of line III1II of FIG. 1; and

FIG. 4 is a complete diagram, partly electrical and partly mechanical, in perspective of parts of the apparatus and machine shown in the previous figures.

With reference to the figures of the drawing, there is shown a machine for developing cinematographic films and comprising a plurality of tanks 1 containing the treatment liquids. The sides of the tanks have, near the base, vertical guides (not shown) each of which accommodates a carriage 2 freely slidable in the vertical direction. Fitted into each carriage 2 is a pin 20 (FIGS. 1 and 3) on which are loosely mounted rollers 21 for supporting the film. At the upper ends of the tank 1, and placed a little to the side, there is a frame 3 (FIGS. 1 and 3) in which are journalled driving shafts 30. Each driving shaft 30 carries loosely mounted on it, some rollers 32 and at least one roller keyed to it, for example, the roller 31 which is made of a material having a high co-eflicient of friction, e.g. rubber. Generally each lower shaft 20 has one roller 21 less than the corresponding upper shaft 30. The film 40 to be treated comes from a spool (not shown) and is wound around the rollers on corresponding shafts 20 and 30, more or less helically making it pass around an upper roller and a lower one of the associated pair of shafts in the same tank. When the film 40 has been wound on all the rollers of one pair it is then wound on the rollers of the following pair of shafts until after being wound on all the rollers of all the pairs of shafts, it is brought to a final collecting bobbin (not shown). In these circumstances presuming the film to be put in motion, and all the driving rollers to be driven at a substantially constant peripheral speed, an equilibrium is established in the system with the speed of the film equal at all points. Any variation in length of the film or of the speed of advancement of the film is expressed in a vertical displacement of the lower axles. If such displacements become frequent and remain a long time there are produced substantial variations in the time for which the film remains in the treatment bath.

Every driving shaft 30 is coupled preferably coaxially to the shaft of an electric motor of the so-called constant couple type which will be described further below. In some cases it may be advantageous in order to operate the motor at a speed near that of its normal speed, to insert a reduction gear between the motor shaft and the driving shaft 30. Each lower carriage 2 is provided with a rod 23 having a part projecting upwards substantially verticallly, the extreme upper portion of which is inserted freely in the bore of a support 24 (FIG. 4) rigid with a fixed part of the machine, for example, the frame 3 (FIGS. 1-3). On the upper end part of each rod 23 are secured two identical adjustable stops 25 and 26 in the form of collars held by respective locking screws, the upper one 25 of which is above the support 24 and the lower one 26 of which is a little below the support 24. Between the latter and the lower stop 26 there is placed on the rod 23 a spring 27 capable of being compressed. As a consequence of the arrangement just described it is obvious that when the carriage 2 and therefore the rod 23 are lowered there will come a point at which the stop 25 meets the support 24. Further action of the film which would tend to cause the carriage 2 to move lower causes a local slackening of the film which as soon as it is produced spreads to the whole system which as stated tends to equilibrium establishing a tension of the film equal at all points. If on the other hand the lower carriage 2 and therefore the rod 23 is raised so that the spring 27 meets the lower face of the support 24 and commences to be compressed then the upward movement meets a resistance which becomes greater as the carriage rises further. This corresponds with an instant local increase of tension in the film which tends to be transmitted to the whole system.

However, means are provided by which, as soon as such variations of tension in the film pass from one upper shaft to the next, they are detected and there are initiated the operations which bring the system back to the desired equilibrium.

In fact between every pair of upper shafts 30, 30' (FIG. 4) the film passes over a roller 6 loosely mounted for rotation in a sensing device 60. The sensing device comprises a lever having its fulcrum at 62, the arm 61' of the lever being loaded by a spring 63 which draws upwardly the pin 64 on which is loosely mounted the roller 6. The arm 61" of the lever is arranged to make or break two or three different electric contacts as explained below.

The force exercised by the spring 63 on the roller 6 is dimensioned such that when the tension in the film is equal or substantially equal throughout, that is to say, when the carriages 2 are not displaced beyond the limits fixed by the stops 25 and 26, the device 60 is in a position of equilibrium in which it does not effect any control.

As already stated previously, the motors 5 must be able to operate at two speeds, that is, they must be able to operate at a speed, for example, the lower one, defining the normal machine speed and at speed slightly greater, i.e. the balancing speed.

In practice it has been found that very suitable motors are monophase motors usually operated at a single voltage, with a single polarity and having an unwound rotor. Such motors are impulse coupled with the rate of variable rotation dependent on the load. Such motors are in fact intended to be single-speed motors but it is possible to operate them at two speeds if they are connected in series with a resistance 50 which can be short-circuited so that the lower speed is obtained when the motor 5 is connected in series with the resistance 50 and the higher speed is obtained when the motor is connected directly to the distribution circuit. If as in the present case, the resistance in series with the motor is a variable resistance, there results the advantage of being able to set the speed of rotation of each motor 5 making it uniform with the others and with the devices feeding film to and removing it from the developing apparatus. It is also possible to vary correspondingly the balance speed of the developer.

This is the solution which in practice has been selected and which has given good results. Such a combination is shown in FIG. 4 with respect to two successive driving devices. To distinguish one device from the other, the equivalent members of the two devices have the same reference numerals which have been primed in the case of one device. To the electricity supply line constituted by the wires 70, 71 are connected, via the terminals 72, 73 and 72', 73' respectively, the motors 5, 5 which have their windings in series with the variable resistances 50, 50-. These resistances can be short-circuited by circuits 51, 51 which can be connected to a single conductor 51" by way of contacts 52, 52' which are normally open. The conductor 51" in its turn is connected by means of a terminal 74 to the wire 70.

When current is introduced to the installation under the conditions in which it is shown, say, in FIG. 4, the motors 5, 5 initially tend to rotate at the same speed and operate in perfect agreement, advancing the same linear quantity of film 40 by means of the rollers 31.

If this constant-rate advance of the film does not occur an operator can adjust the displacement of the rod 23 or 23 by acting on the slides or wipers of the rheostats or potentiometers 50, 50' and thereby control the speed of rotation of the motors 5, 5 to fulfill the requirement for balancing the system. Of course this requires centering of the slides of the rheostats on a frame and entails the constant presence of a trained operator.

In fact, adjustment of the rheostats 50, 50' is not used to remedy temporary imbalances but is used to effect initial adjustment of the speed of rotation of the motors 5, 5'.

When, in spite of perfect setting, the motors 5, 5' do not feed equal quantities of film 40 for any reason whatsoever (the nonuniform rate of linear advance being due, for example, to different coefficients of friction of the driving rollers 31 or to the effect of lengthening of the film by heat expansion or resulting from immersion in chemical baths), a sliding movement of the carriages 2, 2' and of the rods 23, 23' as already described is produced. Up to the point when the displacement is maintained between the predetermined limits defined by the stops 25 and 26 and also by the spring 27, the tension of the film is substantially constant over the whole of its length and corresponds to that tension which keeps the electrical control contact 60" in the set position.

When, however, the slackening or tightening of the film corresponds to oscillation beyond the fixed limits, the balance operation is brought about. Suppose, for example, that for any cause, such as an expansion of the film 40, the carriage 2 and its rod 23 move down until the stop 25 meets the support 24, the resulting excess of film produces almost total nullification of tension in the film 40 in all the spirals associated with the carriage 2. As soon as such loss of tension reaches the length of film over the roller 6, this is retracted (drawn upwardly in FIG. 4) by the spring 63, and the contact 60 is lowered into engagement with the contact 52. The closing of the circuit 51, 51" short circuits the resistance 50 and causes the motor 5 to operate at a higher speed corresponding to the greater voltage now applied to it. Such increase in the speed of rotation of the motor 5 will have the effect of transporting more film 40 while the motor 5' only continues to operate at the normal working speed. Then as soon as the motor 5 has raised the carriage 2 to a point at which the stop 25 no longer touches the support 24, the tension in the film associated with the carriage 2 tends to be restored to the pre-existing value corresponding to the force with which the spring 63 acts on the contact 60" and which corresponds to the condition of the two motors 5 and 5' both operating at the working speed.

Substantially the same explanation as given for the lowering of the carriage 2 applies for the lowering of the carriage 2'. Those conversant with the art will be able to understand on the basis of the explanation given above the action of the system in case of tightening of the film beyond the point at which the carriage 2 or 2' is lifted so as to bring the spring 27 or the spring 27 into action. It will also be obvious to those skilled in the art that the balancing action is so arranged to come into effect only between each pair of driving devices but also between the adjacent devices of adjacent pairs of devices. It is particularly important for the balancing action of the apparatus to be very rapid. Thus, nothing is allowed to obstruct the stops 25 and 26 or the upper end of the spring 27 and these elements are maintained relatively close to one another. This ensures constant treatment times. It will be noted that if the film 40 should be broken, the action of the spring 63 brings a control contact 79 against a contact 7 which is arranged to produce an alarm signal and/ or stop the machine.

In a modified form of the apparatus, control of the apparatus can be effected by the electric control contact connected with the contact 52 or with the contact 52. In this case the electric contact 60" may assume two single positions which would allow the apparatus to operate well. In fact in practice it would be required that the motors ahead of the pair of devices shown (in the direction of movement of the film) rotate faster than the motors behind but adjacent the same pair of devices a change of speed of the two sets of motors so as to have those below rotate faster and those above rotate slower would bring in a few seconds the desired equilibrium with new prevalence of the motors above over those below. This latter embodiment moreover is simpler and more economical.

What I claim is:

1. An apparatus for advancing a continuous strip of film or the like along a processing path, said apparatus comprising a plurality of spatially fixed shafts and corresponding movable shafts, each associated with one of the fixed shafts to form a respective pair; a plurality of axially offset rollers mounted on each of said shafts whereby the continuous strip to be advanced can be wound substantially helically about successive rollers of the fixed and movable shafts of one pair and thence about the rollers of the fixed and movable shafts of a successive pair of fixed and movable shafts; a respective electric motor drivingly connected with at least one of the rollers of each of said fixed shafts for advancing said strip along said path; circuit means including respective resistances connectable with said motors for establishing a normal speed thereof and a compensating speed different from said normal speed for each of said motors; and sensing means responsive to nonuniform movement of said strip along said path'for selectively inserting and removing a respective resistance in circuit with one of said motors to temporarily operate the latter at its compensating speed to restore uniform advance of the strip.

2. An apparatus for advancing a continuous strip of film or the like along a processing path, said apparatus comprising a plurality of spatially fixed shafts and corresponding movable shafts, each associated with one of the fixed shafts to form a respective pair; a plurality of axially offset rollers mounted on each of said shafts whereby the continuous strip to be advanced can be wound substantially helically about successive rollers of the fixed and movable shafts of one pair and thence about the rollers of the fixed and movable shafts of a successive pair of fixed and movable shafts; a respective electric motor drivingly connected with at least one of the rollers of each of said fixed shafts for advancing said strip along said path; circuit means including respective resistances c-onnectable with said motors for establishing a normal Speed thereof and a compensating speed different from said normal speed for each of said motors, and switch means for inserting one of said resistances in circuit with the respective motor while short-circuiting the resistance of a motor of an adjacent pair of shafts; and sensing means responsive to nonuniform movement of said strip along said path for triggering said switch means to temporarily operate the motor with its resistance inserted in circuit therewith at its compensating speed while main-- ciated with an adjacent pair of shafts, rollers and motor in a set and a plurality of such sets are provided along said path, said circuit means being connected to said motors of each set for operating the motors of said set both at a predetermined lower speed upon said sensing means detecting uniform movement of said strip along said path, for operating the upstream motor of the set at a relatively high speed and the downstream motor of the set at a relatively low speed upon detection by said sensing means of an irregularity in the movement of said strip along said path in one direction, and for operating the upstream motor of each set at a relatively low speed while operating the downstream motor of the set at a relatively high speed upon detection by said sensing means of an irregularity in said movement in the opposite direction.

4. The apparatus defined in claim 3 wherein said sensing means has an electrical output and produces a regularity signal representing normal strip tension and an irregularity signal representing abnormal strip tension, said sensing means being responsive to the strip tension.

5. The apparatus defined in claim 4 wherein said sensing means includes a sensing roller engaging said strip, a lever carrying said sensing roller and mounted upon a fulcrum, and spring means bearing upon said lever for retaining said sensing roller against said strip said switch means forming part of said circuit means and being operable by said lever for selectively short-circuiting said resistances, said sensing roller engaging said strip between the pairs of each set.

6. The apparatus defined in claim 4 wherein the movable shaft of each pair is shiftable toward and away from the spatially fixed shaft of the corresponding pair in response to the tension of the strip passing about the rollers of the shafts of the corresponding pair, the movement of said movable shaft controlling at least in part said circuit means.

7. The apparatus defined in claim 6, further comprising spring means acting upon each of said movable shafts to limit the displacement thereof.

8. The apparatus defined in claim 7, further comprising stop means operatively connected with each of said movable shafts for preventing the displacement thereof beyond predetermined limits in the direction of and in the direction away from the corresponding spatially fixed shaft.

9. The apparatus defined in claim 8 wherein each of said movable shafts is provided with a carriage shiftable toward and away from the spatially fixed shaft of each pair, a rod extending from said carriage toward the spatially fixed shaft, a guide member in the region of the corresponding spatially fixed shaft slidably receiving said rod, a pair of adjustable stops forming said stop means with said member and fixed to said rod on opposite sides of said member, and a compression-type coil spring seated against said member and bearing upon said rod while forming said stop means.

10. The apparatus defined in claim 2, further comprising signal means connected with said sensing means for indicating breakage of said strip.

11. The apparatus defined in claim 2, furthercomprising signal means connected with said sensing means for indicating reduced tension of said strip. I

12. The apparatus defined in claim 2, further comprising a housing defining a plurality of vertically elongated upright compartments spaced along said path and adapted to receive respectivefilm-processing solutions, said strip being a photographic or cinematographic film, said spatially fixed shafts of each of said pair being each disposed at an upper end of a respective one of said compartments with the corresponding movable shaft being disposed in the corresponding compartment proximal to the bottom thereof, said movable shafts each being provided with a vertically shiftable carriage, an upright rod fixed to the carriage and extending out of the respective compartment, a guide member on said housing slidably receiving said rod above the respective compartment, a pair of stops adjustably fixed to each rod on opposite sides of the respective guide member for defining the limits of mobility of said movable shafts, and spring means bearing downwardly on said rod for constraining the respective movable shaft against upward movement in the respective compartment, said sensing means including a sensing roller engaging the film between adjacent compartment, a lever fulcnimed on said housing and carrying said sensing roller, a spring bearing upon said lever for biasing same against the film whereby said lever is shiftable from a normal position representing proper film tension in opposite directions into off-normal positions representing excessive and insufficient film tension, respectively, and means connecting said switch means with said lever for operating raid switch means upon displacement of said lever from its normal position into one of its off-normal positions, said switch means having at least two sets of contacts respectively energizable to short-circuit one of the resistances to operate the corresponding motor at an elevated speed while the other motor is maintained at a reduced speed in dependence upon the direction of movement of said lever.

13. The apparatus defined in claim 12 wherein said resistances are adjustable rheostats.

14. The appartus defined in claim 12 wherein said circuit means further comprises a switch actuatable by said lever upon excessive failure of film tension, to signal said failure.

References Cited UNITED STATES PATENTS ALLEN N. KNOWLES, Primary Examiner US. Cl. X.R. 

